output_vcd: Remember samples between packets.

[libsigrok.git] / output / output_vcd.c

/*
 * This file is part of the sigrok project.
 *
 * Copyright (C) 2010 Uwe Hermann <uwe@hermann-uwe.de>
 * Copyright (C) 2011 Bert Vermeulen <bert@biot.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 */

#include <stdlib.h>
#include <string.h>
#include <glib.h>
#include <sigrok.h>
#include "config.h"

struct context {
	int num_enabled_probes;
	int unitsize;
	char *probelist[65];
	int *prevbits;
	GString *header;
	uint64_t prevsample;
};

const char *vcd_header = "\
$date %s $end\n\
$version %s $end\n%s\
$timescale %s $end\n\
$scope module %s $end\n\
%s\
$upscope $end\n\
$enddefinitions $end\n\
$dumpvars\n";

const char *vcd_header_comment = "\
$comment\n  Acquisition with %d/%d probes at %s\n$end\n";

static int init(struct output *o)
{
	struct context *ctx;
	struct probe *probe;
	GSList *l;
	uint64_t samplerate;
	int num_probes, period, i;
	char *samplerate_s, *frequency_s, *timestamp;
	time_t t;

	if (!(ctx = calloc(1, sizeof(struct context))))
		return SIGROK_ERR_MALLOC;

	o->internal = ctx;
	ctx->num_enabled_probes = 0;

	for (l = o->device->probes; l; l = l->next) {
		probe = l->data;
		if (!probe->enabled)
			continue;
		ctx->probelist[ctx->num_enabled_probes++] = probe->name;
	}
	if (ctx->num_enabled_probes > 94) {
		g_warning("VCD only supports 94 probes.");
		return SIGROK_ERR;
	}

	ctx->probelist[ctx->num_enabled_probes] = 0;
	ctx->unitsize = (ctx->num_enabled_probes + 7) / 8;
	ctx->header = g_string_sized_new(512);
	num_probes = g_slist_length(o->device->probes);

	/* timestamp */
	t = time(NULL);
	timestamp = strdup(ctime(&t));
	timestamp[strlen(timestamp)-1] = 0;
	g_string_printf(ctx->header, "$date %s $end\n", timestamp);
	free(timestamp);

	/* generator */
	g_string_append_printf(ctx->header, "$version %s %s $end\n",
			PACKAGE, PACKAGE_VERSION);

	if (o->device->plugin) {
		samplerate = *((uint64_t *) o->device->plugin->get_device_info(
				o->device->plugin_index, DI_CUR_SAMPLERATE));
		if (!((samplerate_s = sigrok_samplerate_string(samplerate)))) {
			g_string_free(ctx->header, TRUE);
			free(ctx);
			return SIGROK_ERR;
		}
		g_string_append_printf(ctx->header, vcd_header_comment,
				 ctx->num_enabled_probes, num_probes, samplerate_s);
		free(samplerate_s);
	}

	/* timescale */
	/* VCD can only handle 1/10/100 (s - fs), so scale up first */
	if (samplerate > MHZ(1))
		period = GHZ(1);
	else if (samplerate > KHZ(1))
		period = MHZ(1);
	else
		period = KHZ(1);
	if (!(frequency_s = sigrok_period_string(period))) {
		g_string_free(ctx->header, TRUE);
		free(ctx);
		return SIGROK_ERR;
	}
	g_string_append_printf(ctx->header, "$timescale %s $end\n", frequency_s);
	free(frequency_s);

	/* scope */
	g_string_append_printf(ctx->header, "$scope module %s $end\n", PACKAGE);

	/* Wires / channels */
	for (i = 0; i < ctx->num_enabled_probes; i++) {
		g_string_append_printf(ctx->header, "$var wire 1 %c %s $end\n",
				(char)('!' + i), ctx->probelist[i]);
	}

	g_string_append(ctx->header, "$upscope $end\n"
			"$enddefinitions $end\n$dumpvars\n");

	if (!(ctx->prevbits = calloc(sizeof(int), num_probes))) {
		g_string_free(ctx->header, TRUE);
		free(ctx);
		return SIGROK_ERR_MALLOC;
	}

	return SIGROK_OK;
}

static int event(struct output *o, int event_type, char **data_out,
		 uint64_t *length_out)
{
	struct context *ctx;
	char *outbuf;

	ctx = o->internal;
	switch (event_type) {
	case DF_END:
		outbuf = strdup("$dumpoff\n$end\n");
		*data_out = outbuf;
		*length_out = strlen(outbuf);
		free(o->internal);
		o->internal = NULL;
		break;
	default:
		*data_out = NULL;
		*length_out = 0;
		break;
	}

	return SIGROK_OK;
}

static int data(struct output *o, char *data_in, uint64_t length_in,
		char **data_out, uint64_t *length_out)
{
	struct context *ctx;
	unsigned int i;
	int p, curbit, prevbit;
	uint64_t sample;
	static uint64_t samplecount = 0;
	GString *out;
	int first_sample = 0;

	ctx = o->internal;
	out = g_string_sized_new(512);

	if (ctx->header) {
		/* The header is still here, this must be the first packet. */
		g_string_append(out, ctx->header->str);
		g_string_free(ctx->header, TRUE);
		ctx->header = NULL;
		first_sample = 1;
	}

	for (i = 0; i <= length_in - ctx->unitsize; i += ctx->unitsize) {
		samplecount++;

		memcpy(&sample, data_in + i, ctx->unitsize);

		if (first_sample) {
			/* First packet. We neg to make sure sample is stored. */
			ctx->prevsample = ~sample;
			first_sample = 0;
		}


		for (p = 0; p < ctx->num_enabled_probes; p++) {
			curbit = (sample & ((uint64_t) (1 << p))) >> p;
			prevbit = (ctx->prevsample & ((uint64_t) (1 << p))) >> p;

			/* VCD only contains deltas/changes of signals. */
			if (prevbit == curbit)
				continue;

			/* Output which signal changed to which value. */
			g_string_append_printf(out, "#%" PRIu64 "\n%i%c\n", samplecount,
					curbit, (char)('!' + p));
		}

		ctx->prevsample = sample;
	}

	*data_out = out->str;
	*length_out = out->len;
	g_string_free(out, FALSE);

	return SIGROK_OK;
}

struct output_format output_vcd = {
	"vcd",
	"Value Change Dump (VCD)",
	DF_LOGIC,
	init,
	data,
	event,
};